Goodbye beautiful IDs

It was a great ride!

IDs look instead of
`TE5BTDc2ZTc3YTMwZGU3MDgzMzllOTliNGExNjVmMjZkMTY1ZmUyZGEyNTUxMjVmODBkMmQzOGMxYWI2ZjAxNzdiM2Q=`
more like `7HcnNSoO1MVvb0p9a9e293152922853e910b8b1a65bb26e225a0568` now.

Regards https://github.com/profanity-im/profanity/issues/1520

We still has our identifier into it to filter MUC reflected messages.

profident maybe should be changed to be longer or be generated upon each
start.

src/xmpp/connection.h

@@ -38,6 +38,8 @@
 
 #include "xmpp/xmpp.h"
 
+#define CON_RAND_ID_LEN 15
+
 void connection_init(void);
 void connection_shutdown(void);
 void connection_check_events(void);